This invention relates to a process for making a thermoplastic article and more particularly to a process for making a fiber reinforced thermoplastic article that can be used as a structural member, such as a cross car beam or a structural instrument panel carrier.
U.S. Pat. No. 5,088,571 issued to Donald L. Burry and Leonard J. Pilato Feb. 18, 1992 discloses a modular instrument panel carrier that comprises a box shaped beam that extends transversely across the vehicle. The box shaped beam is made from two panels of fiber reinforced plastic that have flanged edges that are bonded together. The patent specification does not describe the manufacturing process for the panels or give any particulars for the reinforcement fibers or the plastic.
It is known that continuous fiber reinforced thermosetting plastic articles can be made by pultrusion. Pultrusion is a primary fabrication process for making continuous-length filament reinforced plastic composite profiles. In the common form, reinforcing filaments, such as glass fiber roving, saturated with catalyzed thermoset resin, are continuously pulled through a shaped orifice in a heated steel die. As the two materials, filaments and resin, pass through the die, polymerization of the resin occurs to continuously form a rigid cured profile corresponding to the die orifice shape. Resin materials include rigid and flexible polyesters and combinations thereof, vinyl esters, one-part epoxies that cure like polyesters, and high performance resins based on urethane reaction with vinyl esters and unsaturated polyesters. Reinforcing materials include glass fiber rovings, graphite fibers and nonwoven veils. While this process is capable of making structural members, the articles produced by this process are necessarily limited to straight, constant shaped products or profiles that can be configured by an orifice in a heated steel die or the like because the thermosetting plastic material is hardened permanently after it leaves the heated die.
It is also known from U.S. Pat. No. 3,023,461 granted to Orville B Sherman Mar. 6, 1962 and from U.S. Pat. No. 5,085,821 granted to Shigero Nohara Feb. 4, 1992 that small, hollow, non-structural thermoplastic articles of changing shape, such as double layered bottles, can be made by combining extrusion and blow molding processes. The thermoplastic articles produced by this combined process are not limited to straight, constant shape products or profiles that can be configured by an orifice of an extruder. Indeed, the combined process is capable of producing small, hollow products that are straight or curved and having either constant area and changing shape or changing area and changing shape. However, the physical properties, particularly the strength and structural rigidity, of these hollow thermoplastic articles are limited by the wall thickness and/or hollow shapes that can be generated by the combined process because no reinforcement is used.
On the other hand, it is further known from U.S. Pat. No. 4,731,216 granted to Alvin S. Topolski Mar. 15, 1988 that small, hollow, non-structural thermoplastic articles, such as bottles, can be made by a combined extrusion and blow molding process from a reinforced mixture comprising a thermoplastic matrix having particles of an incompatible thermoplastic material for reinforcement. However, the physical properties, particularly the strength and structural rigidity, of the hollow, reinforced thermoplastic article are limited to those that can be obtained from a mixture that is discontinuous by nature.